This invention relates to a control system for controlling the fluid pressure applied to a pressure-operated actuator, such as a clutch or a brake mechanism, to effect a smooth engagement of the actuator.
In many fluid pressure-operated actuators a gradual, rather than an abrupt, change in applied pressure is desired so that the actuator engages smoothly. A sharp pressure change causes an abrupt engagement which in turn produces high mechanical stresses in the actuator and possible component damage. Various valve arrangements have been developed in the past to apply gradually changing pressures to actuators, but these prior arrangements have reliability problems, require large spaces, are complex in construction, and are relatively expensive. The present invention overcomes all of these shortcomings and obtains smooth, optimum engagement of an actuator by providing, for the actuator, a control system which is of relatively simple and inexpensive construction, requires relatively little space, and is highly reliable in operation.